Traveling grate for heat treating materials

ABSTRACT

A traveling grate for heat treating materials having an endless chain grate with lateral side plates to convey the materials on its upper strand through a heat treating chamber and wherein the chain grate is provided with upstanding side plate members at its lateral edges, each of the side plate members having therein vertical slots open at their upper ends to permit thermal expansion and contraction of such members.

United States Patent 1191 Korting TRAVELING GRATE FOR HEAT TREATINGMATERIALS [75] Inventor: Reinhard Korting, Neubeckum,

Germany [73] Assignee: Polysius AG, Neubeckum, Germany [22] Filed: Sept.4, 1973 [21] Appl. No.: 393,809

[30] Foreign Application Priority Data Oct. 17, 1972 Germany 7238025[U][52] US. Cl 432/245, 432/243, 266/21, 1 10/40 C [51] Int. Cl. F23b 1/22[58] Field Of Search 432/137, 251, 247, 248, 1 432/243, 245; 266/21;110/40 R, 40 C [56] References Cited UNITED STATES PATENTS 1,700,3661/1929 Fahrenwald 432/243 11 1 3,841,829 1451 Oct. 15, 1974 2,006,6127/1935 Williams 432/243 2,045,646 6/1936 Harris 432/245 2,279,689 4/1942Lerner 432/243 3,322,414 5/1967 Boron 266/21 3,393,904 7/1968 Taylor432/243 3,420,512 1/1969 Irvine, Jr. et a1. 266/21 3,548,763 12/1970Farber 266/21 3,563,520 2/1971 Muller 432/245 Primary Examiner-John .1.Camby Assistant Examiner-Henry C. Yuen Attorney, Agent, or Firm-Learman& McCulloch 57] ABSTRACT A traveling grate for heat treating materialshaving an endless chain grate with lateral side plates to convey thematerials on its upper strand through a heat treating chamber andwherein the chain grate is provided with upstanding side plate membersat its lateral edges, each of the side plate members having thereinvertical slots open at their upper ends to permit thermal expansion andcontraction of such members.

6 Claims, 2 Drawing Figures TRAVELING GRATE FOR HEAT TREATING MATERIALSTraveling grates of the endless chain type are employed in heat treatingprocedures of widely different kinds of goods, for example, crude ore,cement raw meal, or fertilizer, whereby these materials might beprocessed in granular form or as pellets. The material to be treated isconveyed on the upper strand of an endless chain grate through the heattreating chamber, which may have a gas temperature range between 800l,200 C. Whereas the individual members of the chain grate are protectedfrom these high temperatures by the layer of the material to be treated,the lateral side plate members, being higher than the chain members ofthe chain grate, have considerably less protection or none at all fromthese temperatures, since the layer of the material slopes at thelateral edges as a result of friction at the wall, and thus cannotprotect the upper edges of these side plate members at all or at leastonly very incompletely. On the other hand, the space beneath the upperstrand of the chain grate is exposed to temperatures between 200 600 C,so that at least the upper side of the side plate members facing theheat treating chamber are subjected to a considera bly stronger heatingthan is the lower side of the side plate members facing away from theheat treating chamber. It follows, therefore, that high thermal stressesoccur within the side plate members, which stresses could easily lead toa destruction of the side plate members, which in turn wouldcauseundesirable interruption of the operation.

An object of the present invention is to construct a traveling grate ofthe type referred to and wherein destruction of the side plate membersof chain grates caused by thermal stress is largely prevented.

in accordance with the invention, the side plate members are providedwith slots to accommodate expansion and contraction at the side facingthe heat treating chamber. By locating these expansion slots in theupper portion of the side plate members, it is possible to reducethermal stress considerably so that resulting destruction of the sideplate members and subsequent interruption of the operation of thetraveling grate can belargely eliminated.

An embodiment of the invention is shown in detail in the followingdescription and drawings wherein:

FIG. 1 is a simplified partial cross section of a traveling grateaccording to the invention; and

FIG. 2 is a side elevation view of a side plate member according to theinvention.

For purposes of simplification, FIG. 1 illustrates merely that portionof the traveling grate-equipment l of the invention, through which upperstrand 2 of a continuously revolving chain grate 3 is conveyedperpendicularly to the plane of the drawing. A layer of material 4 islocated on the top side of the upper strand 2, which material isconveyed through the heat treating chamber 5 located above the upperstrand 2 of the chain grate where gas temperatures of approximately 800l,200 C prevail, whilegas temperatures of approximately 200 600 Cprevail in the region below the upper strand 2 of the chain grate. Thechain members 6 (with grates) sequentially adjacent to each other in thedirection of motion of chain grate 3, are linked to each other by meansof grate bolts 7 (merely indicated by a center line), whereby, dependingupon the width of the traveling grate, a corresponding number of chainmembers 6 are arranged side by side on the grate bolt 7. v

The lateral edges of the grate chain 3 have side plate members 8, 8,which are linked to each other with their ends overlapping by means ofgrate bolts 7 in the same manner as are the chain members 6. As can bereadily seen from the drawing, side plate members 8, 8" extend to ahigher level than that of the chain grate members 6 whereby a lateralboundary is formed for the layer of material 4 which slopes slightly inthis boundary region. Lateral walls la and lb of traveling grateequipment 1 furthermore contain channels 9, 9' for guiding the chaingrate 3 with its lateral edges, including side plate members 8, 8'.

FIG. 2 illustrates a single side plate member 8 in side elevation; sideplate members 8' on the other lateral edge of chain grate 3 areconstructed likewise, but in mirror symmetry. Side plate member 8contains in its lower half boreholes l0, 10' for providing a flexibleconnection of successive neighboring side plate members 8, as well asfor accepting the grate bolts.

For purposes of providing the side plate members, despite greatdifferences in temperature between their top and bottom sides (withrespect to the top and the bottom sides of the upper strand 2 of thechain grate), with a comparatively large resistance to great thermalstresses, i.e., to enable them to accept large thermal stresses withoutbreaking, the side plate members are provided at their upper edge 11, atthe side facing heat treating chambers, with slots 12 to accommodateexpansion and contraction. The number of such expansion slots l2 willgenerally depend upon the size of the chain grate and thus upon the sizeof the side plate members; the embodiment illustrated provides for twoslots 12. The expansion slots 12 provided in the upper half of sideplate member 8 are located between two vertical planes 10a and 10'a,which traverse the center axes of the pivoting point, in this instancethe center axes of the boreholes 10, 10'. It is advantageous for theexpansion slots 12 to be located a distance A away from vertical planes10a and l0a, said distance A corresponding at least to the radius ofboreholes l0, 10' of side plate member 8. Each expansion slot 12 is openat the top side 11 of side plate member 8, and in this instance runsabout perpendicular to the side plate member, said slot having a lengthL of approximately 0.3 to 0.5 times the value of the total height H ofthe side plate member 8.

The side plate member 8 illustrating the invention is only slightlyweakened by the construction and arrangement just described of the slots12 to accommodate expansion and contraction. For side plate members thatare more heavily stressed, it is possible to compensate any resultingweakening without difficulty, by providing suitable reinforcing ribs.

In conclusion it should also be mentioned that individual side platemembers are advantageously shaped at the longitudinal axis such thatsequentially adjacent side plate members interlock, thus forming on bothsides an almost smooth surface covering slots 12 to prevent the escapeof gases. Such forming furthermore makes the individual side platemembers more rigid.

What is claimed is:

1. Traveling grate for heat treating materials conveyed through atreatment chamber comprising a continuous chain grate; and elongateupstanding side plate their upper ends to accommodate expansion andcontraction.

2. Traveling grate according to claim 1 wherein each of said side platemembers has a pair of holes for the reception of bolts, and wherein saidslots are located in the upper half of each side plate member andbetween the two vertical planes traversing the center axes of saidholes.

3. Traveling grate according to claim 2, wherein said expansion slotsare located at a distance away from said vertical planes correspondingat least to the radius of said holes of the side plate member.

4. Traveling grate according to claim 1 wherein each of said side platemember extends to a level higher than that of the chain'grate, andwherein said slots have a length approximatelyOfi to 0.5 times the valueof the total height of the side plate member.

5. Traveling grate according to claim 4 wherein said slots extendperpendicularly from the upper edge of said side plate member.

6. Traveling grate for heat treating materials conveyed through atreatment chamber comprising a continuous chain grate; and upstanding,elongate side plate members at the lateral edges of said chain grate andhaving their adjacent ends in overlapping relation, each of said platemembers being alike and having a body provided adjacent its oppositeends with a pair of spaced apart holes therein for the reception ofbolts, each of said plate members having therein a pair of spaced apartslots extending from the upper edge of said plate member toward butterminating short of the lower edge thereof, said slots being locatedbetween said holes, the locations of said holes and the locations ofsaid slots being such that the overlapping ends of adjacent platemembers cover said slots.

1. Traveling grAte for heat treating materials conveyed through atreatment chamber comprising a continuous chain grate; and elongateupstanding side plate members at the lateral edges of said chain grate,each of said side plate members having slots threin open at their upperends to accommodate expansion and contraction.
 2. Traveling grateaccording to claim 1 wherein each of said side plate members has a pairof holes for the reception of bolts, and wherein said slots are locatedin the upper half of each side plate member and between the two verticalplanes traversing the center axes of said holes.
 3. Traveling grateaccording to claim 2, wherein said expansion slots are located at adistance away from said vertical planes corresponding at least to theradius of said holes of the side plate member.
 4. Traveling grateaccording to claim 1 wherein each of said side plate member extends to alevel higher than that of the chain grate, and wherein said slots have alength approximately 0.3 to 0.5 times the value of the total height ofthe side plate member.
 5. Traveling grate according to claim 4 whereinsaid slots extend perpendicularly from the upper edge of said side platemember.
 6. Traveling grate for heat treating materials conveyed througha treatment chamber comprising a continuous chain grate; and upstanding,elongate side plate members at the lateral edges of said chain grate andhaving their adjacent ends in overlapping relation, each of said platemembers being alike and having a body provided adjacent its oppositeends with a pair of spaced apart holes therein for the reception ofbolts, each of said plate members having therein a pair of spaced apartslots extending from the upper edge of said plate member toward butterminating short of the lower edge thereof, said slots being locatedbetween said holes, the locations of said holes and the locations ofsaid slots being such that the overlapping ends of adjacent platemembers cover said slots.